What is diabetes and how is it diagnosed?

Diabetes is a disease characterized by elevated blood sugar levels. It is extremely common, affecting more than 400 million people worldwide, many of whom aren’t even aware that they have it (1).

If you have diabetes, your blood sugar rises higher than it should after eating a balanced meal. What’s more, it is typically higher than it should be most of the day, including overnight and first thing in the morning.

Diabetes can be diagnosed in one of four ways:

Fastingplasmaglucosetest:Measures your blood sugar after you’ve gone without food for a minimum of 8 hours.

Randombloodglucosetest:Measures your blood sugar at any time of day, whether you’ve eaten recently or not.

Oral glucose tolerance test: Measures your blood sugar at one-hour intervals for up to three hours after you consume a sugary liquid.

HemoglobinA1c:Reflects a 3-month average of your blood sugar levels.

Prediabetes is considered a “stepping stone” towards diabetes. It is diagnosed if your blood sugar is higher than normal but not high enough to meet the criteria for diabetes.

However, prediabetes may progress to diabetes over time, especially if blood sugar remains elevated.

Moreover, prediabetes is increasing even faster than diabetes. It’s estimated that in the US alone, 37% of people over 20 and 51% of people over 65 have prediabetes. By 2030, experts predict that the global number of people with prediabetes will reach a staggering 471 million (2).

Here is a chart showing the A1c, fasting blood sugar and oral glucose tolerance test values used to diagnose diabetes and prediabetes:

In addition, a random blood sugar of 200 mg/dL (11.1 mmol/L) or above can be used to diagnose diabetes if other symptoms are present. These symptoms include:

Excessiveurination:When there is too much sugar in your blood, your kidneys flush it out of your system by increasing urine production.

Excessivethirst:Frequent urination leads to dehydration and causes you to feel extremely thirsty. In fact, you may feel unable to quench your thirst no matter how much you drink.

Increased hunger: Due to hormonal imbalances, your body has problems converting the food you eat into energy. Therefore, it sends signals that drive you to eat.

Unexplainedweightloss:Despite having a good appetite, you may lose weight because your body isn’t able to absorb nutrients from the food you eat.

Fatigue: Because your cells can’t access the fuel they need to function properly, you feel tired, weak and exhausted even when doing very little physical activity.

Although these symptoms are often present at diagnosis — and may be the reason for going to the doctor in the first place — they are also seen in

uncontrolled diabetes. Indeed, they can occur anytime blood sugar is too high, whether you’ve had diabetes for a few weeks or many years.

Living with elevated blood sugar can increase your risk for developing all sorts of serious health problems over time, including:

Heart attack

Stroke

Kidney disease

Nerve damage

Blindness

Gum disease

What’s more, high blood sugar can speed up the aging process by damaging collagen, the main protein in your skin. If your diabetes is poorly controlled, you’re likely to develop wrinkles and sagging skin at an earlier age (3).

In addition, recent research has shown that even prediabetic-range blood sugar may cause many of the same problems seen in diabetes, including increased risk of heart disease and other conditions (4, 5).

Achieving and maintaining blood sugar levels in or near the normal range is extremely important for avoiding these complications.

How diabetes develops and progresses

You may have heard that diabetes is a disease in which the body can’t process sugar or carbs normally. This is certainly true.

If your blood sugar is low, your pancreas secretes glucagon, which tells the liver to break down glycogen into sugar and release it into the bloodstream. This process is called glycogenolysis.

Whenbloodsugarrises,yourpancreassecretesinsulin,whichactsasakeythat allowssugartomovefromthebloodstreamintoyourcells.Inaddition,insulin signals your liver to take up sugar from the blood and store it as glycogen, particularlyafterameal.

What happens in diabetes?

Normally, the beta cells of your pancreas produce small amounts of insulin throughout the day and night in order to keep your blood sugar in a very narrow range of about 80-100 mg/dL (4.4-4.6 mmol/L).

However, in prediabetes and the early stages of type 2 diabetes, your cells don’t respond appropriately to insulin’s action. This is known as insulin resistance.

Essentially, the lock-and-key mechanism is broken, so sugar can’t enter your cells efficiently. Therefore, blood sugar remains elevated, even though there is plenty of insulin available.

The pancreas responds to this by producing more insulin in an attempt to drive the sugar out of the bloodstream and into the insulin-resistant cells. This cycle is repeated over and over on a daily basis, especially after meals, when blood sugar levels are highest.

As this process continues, the cells become progressively more resistant to insulin, which increases the demands on the pancreatic beta cells to produce it in even greater quantities.

Over time, the beta cells lose their ability to make enough insulin to compensate for the insulin resistance. This is known as beta cell failure.

In addition to the beta cells becoming worn out from producing so much insulin, they can also become damaged by prolonged exposure to high blood sugar, which is referred to as glucose toxicity (6,7, 8).

Importantly, this doesn’t happen to every person with diabetes. However, chronically high blood sugar levels greatly increase the likelihood that your pancreas will eventually no longer produce enough insulin.

On the other hand, taking steps to get your blood sugar under control as early as possible can help protect the health of your beta cells, reduce insulin resistance and potentially decrease your need for diabetes medication.

Which type of diabetes do you have?

There are 4 major types of diabetes, and although they share some similarities, they are actually very different diseases.

Type 1diabetes

Type 2diabetes

LADA (Latent Autoimmune Diabetes inAdults)

Gestationaldiabetes

It’s important to know which kind of diabetes you have in order to understand the benefits and limitations of making diet and other lifestyle changes.

Type 1 diabetes

Type 1 diabetes is also called insulin-dependent diabetes. It was previously known as “juvenile diabetes” because it is typically diagnosed in childhood.

However, type 1 diabetes can be diagnosed at any time from infancy to old age, although it occurs much more often in younger individuals. In fact, there have been rare cases of people developing type 1 diabetes in their 90s (9).

People with type 1 diabetes are unable to produce insulin due to an autoimmuneprocessthatdestroystheirpancreaticbetacells.Therefore,they must inject insulin several times a day in order to keep blood sugar under control(10).

However, their insulin needs can be minimized by making certain lifestyle changes.

Type 2 diabetes

Type 2 diabetes is also known as non-insulin-dependent diabetes. It is by far the most common form of diabetes. Indeed, 90% of all people with diabetes have type 2 (11).

Up until 30 years ago, type 2 diabetes was commonly referred to as adult-onset diabetes because it was virtually unheard of in childhood.

However, this has definitely changed in recent years.

As a result of the dramatic increase in obesity, high-carb processed food intake and inactivity among children and adolescents, type 2 diabetes diagnosis now accounts for up to 45% of all new cases of diabetes diagnosed in childhood (12).

As discussed in the previous section, type 2 diabetes is characterized by insulin resistance that forces the pancreas to increase production of insulin to maintain blood sugar control.

If you were diagnosed with type 2 diabetes, your doctor may have prescribed one or more oral medications for you to take. Insulin is typically not required in type 2 diabetes until beta cell failure occurs, if it does.

Fortunately, if you have type 2 diabetes, you may potentially be able to control your blood sugar and prevent further disease progression with lifestyle measures alone.

LADA

LADA (Latent Autoimmune Diabetes in Adults) is a slow, progressive form of autoimmune diabetes that occurs in adults (13, 14).

Sometimes people are misdiagnosed as having type 2 diabetes when they actually have LADA, especially if they are overweight or have other risk factors for type 2.

If you were diagnosed with type 2 diabetes but your blood sugar levels remain very high despite following a healthy diet and taking oral diabetes medication as prescribed, it is possible that you have LADA.

This can be verified by a blood test that checks for antibodies that attack your pancreatic beta cells. In addition, your doctor can order a c-peptide test to measure how much insulin your pancreas is producing.

Importantly, if you have LADA, you will need to inject insulin, regardless of the diet you follow and how much exercise you get.

However, as with type 1 diabetes, making changes to your diet can help reduce your insulin dosage.

Gestational diabetes

Gestational diabetes occurs only in pregnancy as a result of weight gain and hormonal fluctuations that happen during this time.

However, although all women experience these changes during pregnancy, only about 1-14% develop gestational diabetes (15).

Pregnant women are screened for gestational diabetes by taking an oral glucose tolerance test midway through their pregnancy. If diabetes is confirmed, treatment typically includes both lifestyle modification and diabetes medication or insulin.

Although their blood sugar levels often normalize after delivery, women who have had gestational diabetes are 7 times more likely to develop type 2 diabetes than women who haven’t had the condition(16).

Regardless of the type of diabetes you have, there are evidence-based lifestyle strategies that can significantly improve your blood sugar control and may even increase your quality of life.

Riskfactorsyoucanchangeandthoseyou can’t

Although anyone can develop diabetes, certain risk factors significantlyincrease your own odds. Some of these you have no control over; however, many can be substantially reduced by making lifestylechanges.

Risk factors you can’t change

Genes

Although evidence is still emerging in this area, scientists recently identified specific mutations that may be responsible for pancreatic beta cell destruction in type 1 diabetes and impaired glucose and insulin regulation in type 2 diabetes (17, 18).

In addition, a strong family history of type 2 diabetes is a major risk factor for developing the disease.

Infact,ifoneofyourparentshastype2diabetes,youhavea40%increasedrisk of developing it. If both parents have type 2 diabetes, the risk increases to 70% (19).

Some rare forms of diabetes have a strong genetic component, including Maturity Onset Diabetes in the Young (MODY). Although it accounts for only 1-2% of all cases of diabetes, people who inherit the MODY genetic mutation have a 95% risk of developing the disease at some point in their lifetime (20).

Ethnic background

You may be at increased risk for diabetes based on your race and geographic location.

Smoking

It’s well known that smoking increases risk for lung cancer and heartdisease. However, you may not realize that it also places you at greater risk for type 2 diabetes.

Cigarette smoking has been found to increase both the odds of getting diabetes and the likelihood of developing diabetes-related complications, including foot and limb amputations (38, 39).

A large analysis of several studies found that smoking increased the risk of developing diabetes by a whopping 61% in heavy smokers, defined as smoking more than 20 cigarettes per day (40).

Fortunately, tobacco-related diabetes risk may be completely reversible if you quit early enough. One study in middle-aged men who stopped smoking found that after 20 years, these men had the same risk of developing diabetes as people who had never smoked (41).

The take home message here is that rather than focusing on the risk factors you can’t control, it’s important to work on changing the ones that you can.